Switch standard I2C adapter to muxed I2C adapter.

David reported that I2C adapter implementation caused deadlock.
I discussed with Jean and he suggested to implement it as a
multiplexed i2c adapter because tuner I2C bus could be seen like
own I2C segment.
Reported-by: David Howells <dhowells@redhat.com>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>